Thermoplastic vulcanizate compositions

ABSTRACT

In methods for forming thermoplastic vulcanizates, and thermoplastic vulcanizates formed by such methods, a masterbatch comprising one or more additives in a carrier resin comprising propylene- or ethylene-based copolymer is added to the thermoplastic vulcanizate formulation. The resulting thermoplastic vulcanizate may additionally be passed through a 200 mesh or finer screen and thereafter extruded. The thermoplastic vulcanizates may exhibit increased extrusion throughput rates and enhanced surface smoothness.

PRIORITY CLAIM TO RELATED APPLICATIONS

This application is a National Phase Application claiming priority toPCT Application Serial No. PCT/US2015/048364 filed Sep. 3, 2015, andU.S. Provisional Application Ser. No. 62/068,057, filed Oct. 24, 2014,the disclosures of which are fully incorporated herein by theirreference.

FIELD OF THE INVENTION

This invention relates to compositions for forming, and compositionscomprising, thermoplastic vulcanizates, particularly thermoplasticvulcanizates incorporating additives. In addition, this inventionrelates to methods of forming the aforementioned compositions.

BACKGROUND OF THE INVENTION

Thermoplastic vulcanizates (“TPVs”) are a class of thermoplasticcompositions that include finely dispersed cross-linked elastomerparticles forming a disperse phase in a continuous thermoplastic phase.TPVs have the benefit of the elastomeric properties provided by theelastomer phase, with the processability of thermoplastics. TPVs may beproduced by a process that includes dynamic vulcanization—a process ofselectively crosslinking (otherwise referred to alternatively as curingor vulcanizing) the elastomer component during its melt mixing with themolten thermoplastic under intensive shear and mixing conditions withina blend of at least one non-vulcanizing thermoplastic polymer componentwhile at or above the melting point of that thermoplastic. See, forexample U.S. Pat. Nos. 4,130,535; 4,594,390; 6,147,160; 7,622,528; and7,935,763, the entirety of each of which is incorporated by referenceherein.

Conventional plastic processing equipment can extrude, inject, orotherwise mold, and thus press and shape, TPVs into useful products.These thermoplastic vulcanizates can be made light in weight andattractive, with good durability, and can be reprocessed at the end oftheir product life to produce a new product. For these reasons,thermoplastic vulcanizates are widely used in industry, for example asauto parts, such as dashboards and bumpers, air ducts, weatherseals,fluid seals, and other under the hood applications; as gears and cogs,wheels and drive belts for machines; as cases and insulators forelectronic devices; as fabric for carpets, clothes and bedding and asfillers for pillows and mattresses; and as expansion joints forconstruction. They are also widely used in consumer goods, being readilyprocessed, capable of coloration as with other plastics, and providingelastic properties that can endow substrate materials, or portionsthereof, for instance harder plastics or metals, in multi-componentlaminates, with a “soft touch” or rebound properties like rubber.

Thermoplastic vulcanizates can be prepared by dynamic vulcanization inBanbury mixers, roll mixers and other types of shearing, melt processingmixers. Because of the advantages of a continuous process, suchmaterials can be prepared in single screw or multi-screw extruders.

The environment in which thermoplastic vulcanizates are formed and inwhich vulcanization of the rubber constituent occurs is typicallydefined by significant shearing forces, heat, and the presence of avariety of additives, including rubber curing agents and coagents thatfacilitate cross-linking of the rubber. The processing conditions andselection of materials to be included in the TPV can materially impactthe quality of the TPV on extrusion. It is desirable to provide TPVsthat exhibit good physical properties and processability, whilemaintaining excellent extrusion properties. However, balancing thesedesirable characteristics has proven difficult. Extrusion surfacesmoothness (which may also refer to as extrusion surface roughness(ESR)) is a particularly important extrusion property as the ESR maydictate the suitability and aesthetics of a final extruded product. Atthe same time, there continues to be significant room for improvement ofTPV processability, such as extrusion throughput rate. Thus, it isdesirable when formulating and processing TPVs to maintain or improveESR in combination with efforts to improve physical properties andprocessability, such as extrusion throughput rate.

The present invention is directed to compositions and methods forimprovement of processability of TPVs, including extrusion throughputrate, while also maintaining or improving physical characteristics suchas surface smoothness. In certain embodiments, the invention providesTPVs, and methods for making TPVs, that include an at least partiallycross-linked elastomer forming a disperse phase within a continuousphase thermoplastic resin, and that further include a masterbatchadditive. The masterbatch additive may include carbon black and/oranother additive or additives dispersed in a carrier resin. Carbonblack, for example, is typically used to impart a black color to a TPV,and may also impart UV-resistant properties to the TPV. Although carbonblack and/or other additive(s) may be dispersed within a polypropylenecarrier resin to form the masterbatch to be added to the TPV, thepresent inventors have surprisingly found that propylene- orethylene-based copolymers are superior carrier resins for masterbatchesincorporated into TPVs. In particular, when certain propylene- orethylene-based copolymers are used as carrier resins in a masterbatchadded to TPV formulations, the resulting TPVs exhibit enhanced surfacesmoothness and faster extrusion throughput, among other beneficialproperties. Even more surprisingly, these effects are enhanced even ascompared to TPVs that include propylene- or ethylene-based copolymersblended directly into the TPV formulation.

SUMMARY OF THE INVENTION

Accordingly, the present invention in one aspect provides a process forproducing a thermoplastic vulcanizate, in which a TPV formulationcomprising an elastomer component, curing composition, and thermoplasticresin is processed to form a TPV. Processing may include dynamicvulcanization of the elastomer component such that it becomes at leastpartially cross-linked and dispersed within a continuous phasecomprising the thermoplastic resin. In some aspects, carbon black isadded to the TPV formulation during processing via a carbon blackmasterbatch comprising carbon black dispersed in propylene- orethylene-based copolymer carrier resin. In other aspects, one or moreother additives are added to the TPV formulation during processing viaone or more additive masterbatches, each additive masterbatch comprisingone or more of the one or more other additives dispersed in propylene-or ethylene-based copolymer carrier resin. A masterbatch may be added tothe TPV formulation before, during, or after dynamic vulcanization. Incertain aspects, the process may further include extruding the TPVformulation through a 200 mesh or finer screen, which may furtherenhance surface smoothness.

As used herein, a “TPV formulation” refers to the mixture of ingredientsblended or otherwise compiled before or during processing of the TPVformulation in order to form a TPV. This is in recognition of the factthat the ingredients that are mixed together and then processed may ormay not be present in the final TPV in the same amounts added to theformulation, depending upon the reactions that take place among some orall of the ingredients during processing of the mixed ingredients.

The present invention in other aspects may include forming a masterbatchcomprising one or more additives dispersed in a propylene- orethylene-based copolymer carrier resin, and blending the masterbatch, anelastomer component, and a thermoplastic resin to form a TPVformulation. The one or more additives of the masterbatch in particularaspects comprise, or alternatively consist of, carbon black. Theblending may include dynamic vulcanization of the elastomer component inthe thermoplastic resin before, during, or after addition of themasterbatch. The blended TPV formulation may further be extruded orotherwise processed to obtain a TPV comprising the one or moreadditives, propylene- or ethylene-based copolymer, elastomer component,and thermoplastic resin, such that the elastomer component is at leastpartially vulcanized and dispersed within a continuous phase comprisingthe thermoplastic resin. Extrusion or other processing may in someaspects include passing the TPV formulation through a 200 mesh or finerscreen.

In yet further aspects, the invention provides a TPV formed by any ofthe aforementioned processes. In other aspects, the invention provides aTPV comprising an at least partially cross-linked elastomer componentdispersed within a thermoplastic resin, carbon black and/or otheradditive(s), and a propylene- or ethylene-based copolymer, wherein thepropylene- or ethylene-based copolymer is incorporated into the TPV as acarrier resin of the carbon black and/or other additive(s).Alternatively or in addition, the TPV of certain aspects may becharacterized as the product resulting from dynamic vulcanization of acomposition comprising a vulcanizable elastomer component, athermoplastic resin, a curing composition, and a masterbatch comprisingcarbon black (and/or other additive(s)) dispersed in a propylene- orethylene-based copolymer carrier resin.

BRIEF DESCRIPTION OF THE DRAWINGS

The FIGURE is a chart indicating extrusion throughput rates of variousthermoplastic vulcanizate formulations.

DETAILED DESCRIPTION OF THE EMBODIMENTS

As will be described in greater detail below, the present inventiondescribes TPVs, and processes for forming TPVs that include addition ofa masterbatch comprising one or more additives dispersed in a propylene-or ethylene-based copolymer carrier resin. In particular embodiments,the masterbatch is a carbon black masterbatch comprising carbon blackdispersed in the propylene- or ethylene-based copolymer resin. Themasterbatch of various embodiments is suitable for inclusion in any TPVduring manufacture of the TPV. Certain embodiments provide a methodcomprising dynamically vulcanizing a TPV formulation so as to form aTPV. The TPV formulation may comprise an elastomer component, athermoplastic resin, a curing composition, and a masterbatch comprisingone or more additives (e.g., carbon black) dispersed in a propylene- orethylene-based copolymer. The TPV formulation may be processed,including by dynamic vulcanization, to form a TPV comprising (i) theelastomer component at least partially cross-linked and dispersed withina continuous phase of the thermoplastic resin, (ii) the one or moreadditives, (iii) the propylene- or ethylene-based copolymer carrierresin of the one or more additives, and (iv) any byproducts of thedynamic vulcanization reaction and/or any unreacted curing composition.In alternative embodiments, the masterbatch may be added duringprocessing but after dynamic vulcanization. In certain embodiments,other additives (besides the one or more additives in thepreviously-referenced masterbatch) may be included during processing,before or after the dynamic vulcanization, either as direct additions oras additions through additional masterbatches (which may comprise aconventional carrier resin or a propylene- or ethylene-based copolymercarrier resin).

Each component of the TPV formulations of some embodiments will bediscussed in greater detail below, followed by description of theprocessing employed to form TPVs according to various embodiments.

Elastomer Component

Any elastomer suitable for use in the manufacture of TPVs can be used tomanufacture the TPVs of some embodiments of the present invention. Theterm “elastomer” refers to any natural or synthetic polymer exhibitingelastomeric properties, any may be used herein synonymously with“rubber.” The elastomer component of TPVs provided herein should becapable of being vulcanized (i.e., cured or cross-linked). Exemplaryelastomers for use in accordance with the present invention may includeunsaturated non-polar elastomers, monoolefin copolymer elastomerscomprising non-polar, elastomer copolymers of two or more monoolefins(EP elastomer), which may be copolymerized with at least one polyene,usually a diene (EPDM elastomer). EPDM (ethylene-propylene-dieneelastomer) is a polymer of ethylene, propylene and one or morenon-conjugated diene(s), and the monomer components may be polymerizedusing Ziegler-Natta, metallocene, or other organometallic compoundcatalyzed reactions. In the event that the copolymer is prepared fromethylene, alpha-olefin, and diene monomers, the copolymer may bereferred to as a terpolymer or even a tetrapolymer in the event thatmultiple olefins or dienes are used.

Satisfactory non-conjugated dienes include 5-ethylidene-2-norbornene(referred to as ENB or EP(ENB)DM); 1,4-hexadiene (HD);5-methylene-2-norbornene (MNB); 1,6-octadiene; 5-methyl-1,4-hexadiene;3,7-dimethyl-1,6-octadiene; 1,3-cyclopentadiene; 1,4-cyclohexadiene;dicyclopentadiene (DCPD); 5-vinyl-2-norbornene (referred to as VNB orEP(VNB)DM); divinyl benzene, and the like, or combinations thereof. Suchelastomers have the ability to produce thermoplastic vulcanizates with acure state generally in excess of about 95 percent while maintainingphysical properties attributable to the crystalline or semi-crystallinepolymer. EP elastomer and EPDM elastomer with intrinsic viscosity (11)measured in Decalin at 135° C. between 0.1 to 10 dl/gram are preferred.In a particularly preferred embodiment, the elastomer comprises EPDM.

The elastomeric copolymers may contain from about 20 to about 90 molepercent ethylene units derived from ethylene monomer. Preferably, thesecopolymers contain from about 40 to about 85 mole percent, and even morepreferably from about 50 to about 80 mole percent ethylene units.Furthermore, where the copolymers contain diene units, the diene unitscan be present in an amount from about 0.1 to about 5 mole percent,preferably from about 0.1 to about 4 mole percent, and even morepreferably from about 0.15 to about 2.5 mole percent. The balance of thecopolymer will generally be made up of units derived from alpha-olefinmonomers. Accordingly, the copolymer may contain from about 10 to about80 mole percent, preferably from about 15 to about 50 mole percent, andmore preferably from about 20 to about 40 mole percent alpha-olefinunits derived from alpha-olefin monomers. The foregoing mole percentagesare based upon the total moles of the polymer.

The elastomer component may comprise any one or more other suitableelastomeric copolymer capable of being at least partially vulcanized,such as butyl elastomers, natural rubbers, and any other elastomer(synthetic or natural) suitable for inclusion in a TPV, including thosedisclosed in U.S. Pat. Nos. 7,935,763 and 8,653,197, the entirety ofeach of which is hereby incorporated by reference.

Elastomers, especially those in the high end of the molecular weightrange, are often oil extended in the manufacturing process and can bedirectly processed as such in accordance with the invention process.That is, an elastomer component included in a TPV according to someembodiments comprises both elastomer and extender oil.

Thermoplastic Resins

Any thermoplastic resin suitable for use in the manufacture ofthermoplastic vulcanizates can be employed as the thermoplastic resin ofvarious embodiments, including amorphous, crystalline, orsemi-crystalline thermoplastics. In general, any thermoplastic describedin U.S. Pat. No. 7,935,763, previously incorporated by reference herein,is suitable.

In particular embodiments, the thermoplastic resin may comprise one ormore crystallizable polyolefins that are formed by polymerizingalpha-olefins such as ethylene, propylene, 1-butene, 1-hexene, 1-octene,2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene,5-methyl-1-hexene, and mixtures thereof. For example, knownethylene-based homo- and copolymers having ethylene crystallinity aresuitable. Commercial products include high density polyethylene (HDPE),linear low density polyethylene (LLDPE), and very low densitypolyethylene (VLDPE, or plastomers). Propylene-based homopolymers andcopolymers, such as isotactic polypropylene and crystallizablecopolymers of propylene and ethylene or other C4-C10 alpha-olefins, ordiolefins, having isotactic propylene crystallinity, are preferred.Copolymers of ethylene and propylene or ethylene or propylene withanother alpha-olefin such as 1-butene, 1-hexene, 1-octene,2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene,5-methyl-1-hexene or mixtures thereof are also suitable. These willinclude reactor polypropylene copolymers and impact polypropylenecopolymers, whether block, random or of mixed polymer synthesis.

The crystalline or semi-crystalline thermoplastics generally have a peak“melting point” (“Tm”) which is defined as the temperature of thegreatest heat absorption within the range of melting of the sample. TheTm of the thermoplastics of some embodiments may be within the rangefrom a low of any one of about 40, 50, 60, 70, 75, 80, 85, 90, 95, 100,105, 110, 115, and 120° C. to a high of any one of about 170, 180, 190,200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330,340, 350° C. In particular example embodiments, the Tm is within therange from about 40° C. to about 350° C.; from about 75° C. to about210° C.; from about 85° C. to about 180° C.; from about 90° C. to about180° C.; or from about 120° C. to about 170° C. The glass transitiontemperature (Tg) of these thermoplastics is from about −25° C. to about10° C., preferably from about −5 to about 5° C. More generally speaking,including the semi-crystalline and glassy polar thermoplastics, usefulthermoplastics will have a Tg of up to and greater than 100° C., andeven greater than 150° C. The characterizing temperatures are determinedby DSC according to the test method of ASTM D-3418.

A thermoplastic according to particular embodiments comprises highlycrystalline isotactic or syndiotactic polypropylene. This polypropylenegenerally has a density of from about 0.85 to about 0.91 g/cc, with thelargely isotactic polypropylene having a density of from about 0.90 toabout 0.91 g/cc. Also, high and ultra-high molecular weightpolypropylene that has a fractional melt flow rate is highly preferred.These polypropylene resins are characterized by a melt flow rate that isfrom 0.2 to 3000 dg/min and more preferably less than 1.2 dg/min, andmost preferably less than or equal to 0.8 dg/min per ASTM D-1238. Meltflow rate is a measure of how easily a polymer flows under standardpressure, and is measured by using ASTM D-1238 at 230° C. and 2.16 kgload.

The thermoplastic resin may furthermore contain additional components,such as any of those additional components described in U.S. Pat. No.7,935,763 in connection with the thermoplastic resin. For instance, itmay include additional non-crosslinkable elastomers, including non-TPVthermoplastics and thermoplastic elastomers. Examples includepolyolefins such as polyethylene homopolymers, and copolymers with oneor more C₃-C₈ alpha-olefins.

Curing Composition

A curing composition of some embodiments comprises one or more curingagents. Suitable curing agents include any of those known to thoseskilled in the art for processing vulcanizable elastomer, or moreparticularly, thermoplastic vulcanizates. Curing compositions accordingto various embodiments may include any curing agent and/or coagents, andmay further include any method of including a curing agent and/orcoagent, as discussed in U.S. Pat. No. 8,653,197 (previouslyincorporated by reference herein) and in U.S. Pat. No. 8,653,170, theentirety of which is also hereby incorporated by reference.

Suitable curing agents include one or more of silicon hydrides (whichmay effect hydrosilation cure), phenolic resins, peroxides, free radicalinitiators, sulfur, zinc metal compounds, and the like. The namedcuratives are frequently used with one or more coagents that serve asinitiators, catalysts, etc. for purposes of improving the overall curestate of the elastomer. For instance, the curing composition of someembodiments includes one or both of zinc oxide (ZnO) and stannouschloride (SnCl₂). The curing composition may be added in one or morelocations, including the feed hopper of a melt mixing extruder. In someembodiments, the curing agent and any additional coagents may be addedto the TPV formulation together; in other embodiments, one or morecoagents may be added to the TPV formulation at different times from anyone or more of the curing agents, as the TPV formulation is undergoingprocessing to form a TPV (discussed in greater detail below).

Curing agents in particular embodiments may include one or more phenolicresins. Suitable phenolic resins include those disclosed in U.S. Pat.Nos. 2,972,600; 3,287,440; 5,952,425; and 6,437,030 (each of which isincorporated by reference herein), and preferred phenolic resins includethose referred to as resole resins, and discussed in detail in U.S. Pat.No. 8,653,197 (previously incorporated by reference herein). In certainembodiments in which the curing composition includes phenolic resin, thecuring composition also includes one or both of ZnO and SnCl₂.

In addition to the ZnO and SnCl₂, the curing composition of someembodiments also or instead includes any other suitable co-agent, suchas triallylcyanurate, triallyl isocyanurate, triallyl phosphate, sulfur,N-phenyl-bis-maleamide, zinc diacrylate, zinc dimethacrylate, divinylbenzene, 1,2-polybutadiene, trimethylol propane trimethacrylate,tetramethylene glycol diacrylate, trifunctional acrylic ester,dipentaerythritolpentacrylate, polyfunctional acrylate, retardedcyclohexane dimethanol diacrylate ester, polyfunctional methacrylates,acrylate and methacrylate metal salts, oximer for e.g., quinone dioxime,and the like.

Masterbatch

TPV formulations of the present invention may also include a masterbatchcomprising one or more additives dispersed in a carrier resin comprisingpropylene- or ethylene-based copolymer. In some embodiments, the one ormore additives may include any additive suitable for incorporation intoa TPV via a masterbatch (e.g., any additive suitable for dispersion in acarrier resin, thereby forming a masterbatch which may be incorporatedinto a TPV). Examples include fillers, extenders, pigmentation agents,and the like. Particular examples include conventional inorganics suchas calcium carbonate, clays, silica, talc, titanium dioxide, as well asorganic and inorganic nanoscopic fillers.

In particular embodiments, the masterbatch comprises, consistsessentially of, or consists of, carbon black dispersed in a propylene-or ethylene-based copolymer carrier resin. By “consists essentially of,”it is meant with respect to the carrier resin that the properties of thecarrier resin will remain within the bounds of properties of thepropylene- or ethylene-based copolymers of various embodiments(discussed in greater detail below). With respect to the carbon blackdispersed in the masterbatch, “consists essentially of” means that anycomponent(s) dispersed within the carrier resin other than carbon blackare of a nature (and/or a sufficiently small amount) such that theproperties of the TPV formulation (and resulting TPV after processing)are no different than they would have been in the complete absence ofany such additional component(s). In particular, such properties includesurface smoothness and extrusion throughput rate.

Carbon Black Particles in the Masterbatch

The carbon black of the masterbatch according to some embodimentscomprises particles of any conventional type of carbon black (e.g.,acetylene black, channel black, furnace black, lamp black, thermalblack) produced by incomplete combustion of petroleum products. Typicalparticle diameters may range from a low of any one of about 5, 10, 15,20, 25, 30, 35, and 40 nm to a high of any one of about 50, 60, 70, 80,90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220,230, 240, 250, 260, 270, 280, 290, 300, 310, 320, and 330 nm. Carbonblack particles may form aggregates ranging in size (e.g., diameter whenthe aggregate is approximated as a sphere) from a low of any one ofabout 90, 95, 100, 105, 110, and 115 nm to a high of any one of about200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850,and 900 nm, and/or agglomerates ranging in size from a low of any one ofabout 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 microns to a high of about 90,100, 150, 200, 250, 300, 350, and 400 microns, or larger.

In certain embodiments, the carbon black imparts UV protection and/orcoloring (i.e., black pigmentation) to a TPV.

Other Additives in the Masterbatch

As noted, the masterbatch may also or instead comprise one or more otheradditives dispersed within the carrier resin. Again, particular examplesinclude fillers, extenders, pigmentation agents, and the like (e.g.,conventional inorganics such as calcium carbonate, clays, silica, talc,titanium dioxide, as well as organic and inorganic nanoscopic filler).

Propylene- or Ethylene-Based Copolymer Carrier Resin

The masterbatch carrier resin comprises a propylene- or ethylene-basedcopolymer. In general, the propylene- or ethylene-based copolymer mayhave (i) a density between about 0.850 and about 0.920 g/cm³, or inother embodiments between about 0.860 and about 0.910 g/cm³; and (ii) amelt index (MI) between about 0.05 and about 50 g/10 min, or in otherembodiments between about 0.1 and about 30 g/10 min.

Density as used herein is reported at room temperature as measured inaccordance with ASTM D-1505, as set forth by ASTM International as ofOctober 2014 in ASTM D1505-10, Standard Test Method for Density ofPlastics by the Density-Gradient Technique, ASTM International, WestConshohocken, Pa., 2010 (www.astm.org), the entirety of which is herebyincorporated by reference herein. MI as used herein is determined inaccordance with ASTM D-1238 at 190° C. and 2.16 kg weight, as set forthby ASTM International as of October 2014 in ASTM D1238-13, Standard TestMethod for Melt Flow Rates of Thermoplastics by Extrusion Plastometer,ASTM International, West Conshohocken, Pa., 2013 (www.astm.org), theentirety of which is incorporated by reference herein. Thus, any densityand/or MI recited herein may be as determined in a manner consistentwith each of these respective standards (ASTM D1505; ASTM D-1238).

Further, as used herein, a copolymer of propylene and ethylene is“propylene-based” when propylene-based monomers form the plurality ofmonomers in the copolymer, based on the total weight of the copolymer(i.e., propylene-based monomers are present in the copolymer in largerwt % than any other single monomer). Similarly, a copolymer of propyleneand ethylene is “ethylene-based” when ethylene-based monomers form theplurality of monomers in the copolymer. Propylene-based copolymers willbe indicated by naming propylene first (e.g., “propylene-ethylenecopolymers” or “propylene-α-olefin copolymers”), and likewise forethylene-based copolymers (e.g., “ethylene-propylene copolymers” or“ethylene-α-olefin copolymers”). A copolymer of propylene and/orethylene may optionally include one or more additional comonomers.

In certain embodiments, the carrier resin may consist or consistessentially of the one or more propylene- or ethylene-based copolymersaccording to various embodiments described herein. By “consistessentially of” in this context, it is meant that the carrier resincontains no polymer other than the one or more propylene- orethylene-based copolymers in amounts sufficient to modify the properties(particularly one or more of H_(f), melt flow rate, and melt index) ofthe carrier resin compared to a carrier resin consisting of the one ormore propylene- or ethylene-based copolymers.

Propylene- or ethylene-based copolymers according to certain preferredembodiments may include any one or more of: a propylene-α-olefincopolymer; an ethylene-α-olefin copolymer; and an ethylene-propylenecopolymer rubber. Each will be discussed in turn in greater detailbelow.

Propylene-α-Olefin Copolymer Carrier Resins

In several embodiments, the carrier resin comprises or consists of apropylene-α-olefin copolymer which is a random copolymer havingcrystalline regions interrupted by non-crystalline regions. Not intendedto be limited by any theory, it is believed that the non-crystallineregions may result from regions of non-crystallizable polypropylenesegments and/or the inclusion of comonomer units. The crystallinity andthe melting point of the propylene-α-olefin copolymer are reducedcompared to highly isotactic polypropylene by the introduction of errors(stereo and region defects) in the insertion of propylene and/or by thepresence of comonomer. The propylene-α-olefin copolymer comprisespropylene-derived units and units derived from at least one of ethyleneor a C₄-C₁₀ alpha-olefin, and optionally a diene-derived unit. Thecopolymer contains at least about 60 wt % propylene-derived units byweight of the propylene-α-olefin copolymer. In some embodiments, thepropylene-α-olefin copolymer is a propylene-α-olefin copolymer elastomerhaving limited crystallinity due to adjacent isotactic propylene unitsand a melting point as described herein. In other embodiments, thepropylene-α-olefin copolymer is generally devoid of any substantialintermolecular heterogeneity in tacticity and comonomer composition, andalso generally devoid of any substantial heterogeneity in intramolecularcomposition distribution.

The propylene-α-olefin copolymer contains greater than about 50 wt %,preferably greater than about 60 wt %, more preferably greater thanabout 65 wt %, even more preferably greater than about 75 wt % and up toabout 99 wt % propylene-derived units, based on the total weight of thepropylene-α-olefin copolymer. In some preferable embodiments, thepropylene-α-olefin copolymer includes propylene-derived units in anamount based on the weight of propylene-α-olefin copolymer of from about75 wt % to about 95 wt %, more preferably about 75 wt % to about 92.5 wt%, and even more preferably about 82.5 wt % to about 92.5 wt %, and mostpreferably about 82.5 wt % to about 90 wt %. Correspondingly, the units,or comonomers, derived from at least one of ethylene or a C₄-C₁₀alpha-olefin may be present in an amount of about 1 wt % to about 35 wt%, or preferably about 5 wt % to about 35 wt %, more preferably about 5wt % to about 25 wt %, even more preferably about 7.5 wt % to about 25wt %, even more preferably about 7.5 wt % to about 20 wt %, even morepreferably from about 8 wt % to about 17.5 wt %, and most preferablyabout 10 wt % to 17.5 wt %, based on the total weight of thepropylene-α-olefin copolymer.

The propylene-α-olefin copolymer may have a heat of fusion of about 50J/g or less, melting point of about 100° C. or less, and crystallinityof about 2% to about 65% of isotactic polypropylene, and preferably amelt flow rate (“MFR”) of less than 800 g/10 min (dg/min), as measuredaccording to ASTM D-1238 at 230° C. and 2.16 kg weight, which is alsodetermined as described as of October 2014 in ASTM D1238-13, StandardTest Method for Melt Flow Rates of Thermoplastics by ExtrusionPlastometer, previously incorporated by reference. In particularembodiments, the propylene-α-olefin copolymer may have an MFR rangingfrom a low of any one of about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,and 20 g/10 min, to a high of any one of about 15, 16, 17, 18, 19, 20,21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, 45, 50, 75, 100, 125,150, and 200 g/10 min, provided the high is greater than or equal to thelow. Thus, for example, the MFR of propylene-α-olefin copolymeraccording to certain embodiments may be within the range of about 15 toabout 25 g/10 min, or about 18 to 22 g/10 min, or about 20 g/10 min.

Instead or in addition, a propylene-α-olefin copolymer of someembodiments may be characterized according to its melt index, asmeasured according to ASTM D-1238 at 190° C. and 2.16 kg weight. Thepropylene-α-olefin copolymer may have a melt index ranging from a low ofany one of about 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0,2.5, 3.0, 3.5, 4.0, and 4.5 g/10 min to a high of any one of about 8.0,8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 15.0, 20.0, 30.0, 40.0, and50.0 g/10 min.

The propylene-α-olefin copolymer may comprise more than one comonomer.Preferred embodiments of a propylene-α-olefin copolymer having more thanone comonomer include propylene-ethylene-octene,propylene-ethylene-hexene, and propylene-ethylene-butene copolymers.

In some embodiments where more than one comonomers derived from at leastone of ethylene or a C₄-C₁₀ alpha-olefin are present, the amount of eachcomonomer may be less than about 5 wt % of the propylene-α-olefincopolymer, but the combined amount of comonomers by weight of thepropylene-α-olefin copolymer is about 5 wt % or greater.

In preferred embodiments, the comonomer is ethylene, 1-hexene, or1-octene, and preferably in an amount of about 5 wt % to about 25 wt %,about 5 wt % to about 20 wt %, about 5 wt % to about 16 wt %, about 6 wt% to about 18 wt %, about 8 wt % to about 20 wt %, about 9 wt % to about13 wt %, or in some embodiments about 10 wt % to about 12 wt % based onthe weight of the propylene-α-olefin copolymer. Correspondingly, incertain of these embodiments, the propylene-α-olefin copolymer maycomprise about 75 wt % to about 95 wt %, about 80 wt % to about 95 wt %,about 84 wt % to about 95 wt %, about 82 wt % to about 94 wt %, about 80wt % to about 92 wt %, about 87 wt % to about 91 wt %, or in someembodiments about 88 wt % to about 90 wt % propylene-derived units.

In one embodiment, the propylene-α-olefin copolymer comprisesethylene-derived units. The propylene-α-olefin copolymer may compriseabout 5 wt % to about 35 wt %, preferably about 5 wt % to about 25 wt %,about 7.5 wt % to about 20 wt %, about 9 wt % to about 13 wt %, about 10wt % to about 12 wt %, or about 10 wt % to about 17.5 wt %, ofethylene-derived units by weight of the propylene-α-olefin copolymer. Insome embodiments, the propylene-α-olefin copolymer consists essentiallyof units derived from propylene and ethylene, i.e., thepropylene-α-olefin copolymer does not contain any other comonomer in anamount typically present as impurities in the ethylene and/or propylenefeedstreams used during polymerization or an amount that wouldmaterially affect the heat of fusion, melting point, crystallinity, ormelt flow rate of the propylene-α-olefin copolymer, or any othercomonomer intentionally added to the polymerization process. In suchembodiments, then, the propylene-ethylene copolymer would comprise thebalance propylene-derived units in addition to ethylene-derived units inany one of the above-listed ranges.

In some embodiments, diene comonomer units are included in thepropylene-α-olefin copolymer. Examples of the diene include, but notlimited to, 5-ethylidene-2-norbornene, 5-vinyl-2-norbornene, divinylbenzene, 1, 4-hexadiene, 5-methylene-2-norbornene, 1, 6-octadiene,5-methyl-1, 4-hexadiene, 3, 7-dimethyl-1, 6-octadiene, 1,3-cyclopentadiene, 1, 4-cyclohexadiene, dicyclopentadiene, or acombination thereof. The amount of diene comonomer is equal to or morethan 0 wt %, or 0.5 wt %, or 1 wt %, or 1.5 wt % and lower than, orequal to, 5 wt %, or 4 wt %, or 3 wt % or 2 wt % based on the weight ofpropylene-α-olefin copolymer.

The propylene-α-olefin copolymer has H_(f) equal to or less than any oneof about 50, 45, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27,26, 25, 24, 23, 22, 21, and 20 J/g. Suitable propylene-α-olefincopolymer of some embodiments may have a lower limit H_(f) of any one ofabout 0.5, 1.0, 1.5, 2.0, 3.0, 4.0, 5.0, 6.0, and 7.0 J/g.

The propylene-α-olefin copolymer may have a percent crystallinity, asdetermined according to the DSC procedure described herein, of about 2%to about 65%, preferably about 0.5% to about 40%, preferably about 1% toabout 30%, and more preferably about 5% to about 35%, of isotacticpolypropylene. The thermal energy for the highest order of propylene(i.e., 100% crystallinity) is estimated at 189 J/g. In some embodiments,the copolymer has a crystallinity in the range of about 0.25% to about25%, or about 0.5% to about 22% of isotactic polypropylene.

In some embodiments, the propylene-derived units of thepropylene-α-olefin copolymer have an isotactic triad fraction of about50% to about 99%, more preferably about 65% to about 97% and morepreferably about 75% to about 97%. In other embodiments, thepropylene-α-olefin copolymer has a triad tacticity as measured by ¹³CNMR, of about 75% or greater, about 80% or greater, about 82% orgreater, about 85% or greater, or about 90% or greater.

The triad tacticity of a polymer is the relative tacticity of a sequenceof three adjacent propylene units, a chain consisting of head to tailbonds, expressed as a binary combination of m and r sequences. It isusually expressed as the ratio of the number of units of the specifiedtacticity to all of the propylene triads in the propylene-α-olefincopolymer. The triad tacticity (mm fraction) of a propylene copolymercan be determined from a ¹³C NMR spectrum of the propylene copolymer.The calculation of the triad tacticity is described in the U.S. Pat. No.5,504,172, the entire contents of which are incorporated herein byreference.

The propylene-α-olefin copolymer may have a single peak meltingtransition as determined by DSC. In one embodiment, the copolymer has aprimary peak transition of about 90° C. or less, with a broadend-of-melt transition of about 110° C. or greater. The peak “meltingpoint” (“T_(m)”) is defined as the temperature of the greatest heatabsorption within the range of melting of the sample. However, thecopolymer may show secondary melting peaks adjacent to the principalpeak, and/or at the end-of-melt transition. For the purposes of thisdisclosure, such secondary melting peaks are considered together as asingle melting point, with the highest of these peaks being consideredthe Tm of the propylene-α-olefin copolymer. The propylene-α-olefincopolymer may have a Tm of about 100° C. or less, about 90° C. or less,about 80° C. or less, or about 70° C. or less. In one embodiment, thepropylene-α-olefin copolymer has a Tm of about 25° C. to about 100° C.,about 25° C. to about 85° C., about 25° C. to about 75° C., or about 25°C. to about 65° C. In some embodiments, the propylene-α-olefin copolymerhas a Tm of about 30° C. to about 80° C., preferably about 30° C. to 70°C.

Differential scanning calorimetric (“DSC”) data was obtained using aPerkin-Elmer DSC 7. About 5 mg to about 10 mg of a sheet of the polymerto be tested was pressed at approximately 200° C. to 230° C., thenremoved with a punch die and annealed at room temperature for 48 hours.The samples were then sealed in aluminum sample pans. The DSC data wasrecorded by first cooling the sample to −50° C. and then graduallyheating it to 200° C. at a rate of 10° C./minute. The sample was kept at200° C. for 5 minutes before a second cooling-heating cycle was applied.Both the first and second cycle thermal events were recorded. Areasunder the melting curves were measured and used to determine the heat offusion and the degree of crystallinity. The percent crystallinity (X %)was calculated using the formula, X %=[area under the curve(Joules/gram)/B(Joules/gram)]*100, where B is the heat of fusion for thehomopolymer of the major monomer component. These values for B werefound from the Polymer Handbook, Fourth Edition, published by John Wileyand Sons, New York 1999. A value of 189 J/g (B) was used as the heat offusion for 100% crystalline polypropylene. The melting temperature wasmeasured and reported during the second heating cycle (or second melt).

In one or more embodiments, the propylene-α-olefin copolymer may have aMooney viscosity [ML (1+4) @ 125° C.], as determined according to ASTMD-1646, of less than 100, in other embodiments less than 75, in otherembodiments less than 60, and in other embodiments less than 30. As usedherein, Mooney viscosity is reported using the format: Rotor ([pre-heattime, min.]+[shearing time, min.] @ measurement temperature, ° C.), suchthat ML (1+4 @ 125° C.) indicates a Mooney viscosity determined usingthe ML or large rotor according to ASTM D1646-99, for a pre-heat time of1 minute and a shear time of 4 minutes, at a temperature of 125° C.Unless otherwise specified, Mooney viscosity is reported herein asML(1+4 @ 125° C.) in Mooney units according to ASTM D-1646.

The propylene-α-olefin copolymer may have a density of about 0.850 g/cm³to about 0.920 g/cm³, about 0.860 g/cm³ to about 0.900 g/cm³, preferablyabout 0.860 g/cm³ to about 0.890 g/cm³, at room temperature as measuredper ASTM D-1505.

The propylene-α-olefin copolymer may have a weight average molecularweight (“Mw”) of about 5,000 to about 5,000,000 g/mole, preferably about10,000 to about 1,000,000 g/mole, and more preferably about 50,000 toabout 400,000 g/mole; a number average molecular weight (“Mn”) of about2,500 to about 2,500,00 g/mole, preferably about 10,000 to about 250,000g/mole, and more preferably about 25,000 to about 200,000 g/mole; and/ora z-average molecular weight (“Mz”) of about 10,000 to about 7,000,000g/mole, preferably about 80,000 to about 700,000 g/mole, and morepreferably about 100,000 to about 500,000 g/mole. The propylene-α-olefincopolymer may have a molecular weight distribution (“MWD”) of about 1.5to about 20, or about 1.5 to about 15, preferably about 1.5 to about 5,and more preferably about 1.8 to about 5, and most preferably about 1.8to about 4.

The propylene-α-olefin copolymer may have an Elongation at Break of lessthan about 2000%, less than about 1000%, or less than about 800%, asmeasured per ASTM D412.

Processes suitable for preparing the propylene-α-olefin copolymer may insome embodiments include metallocene-catalyzed or Ziegler-Nattacatalyzed processes, including solution, gas-phase, slurry, and/orfluidized bed polymerization reactions. Suitable polymerizationprocesses are described in, for example, U.S. Pat. Nos. 4,543,399;4,588,790; 5,001,205; 5,028,670; 5,317,036; 5,352,749; 5,405,922;5,436,304; 5,453,471; 5,462,999; 5,616,661; 5,627,242; 5,665,818;5,668,228; and 5,677,375; PCT publications WO 96/33227 and WO 97/22639;and European publications EP-A-0 794 200, EP-A-0 802 202 and EP-B-634421, the entire contents of which are incorporated herein by reference.

Ethylene-α-Olefin Copolymer Carrier Resins

In some embodiments, the carrier resin may additionally or insteadinclude, or consist of, one or more ethylene-α-olefin copolymers.Suitable α-olefin comonomers include any one or more of a C₃ to C₁₀α-olefin-based monomer. In certain embodiments, the α-olefin is one orboth of butene and octene (e.g., ethylene-butene and/or ethylene-octenecopolymers).

In some embodiments, the ethylene-α-olefin copolymer includesethylene-based units in an amount greater than or equal to any one ofabout 60, 65, 70, 75, 80, 85, 90, and 95 wt %, by weight of theethylene-α-olefin copolymer. In certain of these embodiments, theethylene-based unit content of the ethylene-α-olefin copolymer may havean upper limit of any one of about 99, 95, 90, 85, 80, 75, and 70 wt %,by weight of the ethylene-α-olefin copolymer, provided that the upperlimit is greater than or equal to the lower limit. In some embodiments,the comonomer is present in an amount greater than or equal to any oneof about 1, 5, 10, 15, 20, 25, and 30 wt %, by weight of theethylene-α-olefin copolymer; and in an amount less than or equal to anyone of about 40, 35, 30, 25, 20, 15, 10, and 5 wt %, by weight of theethylene-α-olefin copolymer, provided that the upper limit is greaterthan or equal to the lower limit.

The ethylene-α-olefin copolymer of some embodiments has a density ofabout 0.850 to about 0.920 g/cm³. In certain embodiments, theethylene-α-olefin copolymer has a density within the range of about0.865 to about 0.910 g/cm³, or from about 0.8675 to about 0.910 g/cm³.In various embodiments, the ethylene-α-olefin copolymer may have adensity within the range of any one of about 0.850, 0.860, 0.865, 0.870,0.875, 0.880, and 0.885 g/cm³ to any one of about 0.900, 0.905, 0.910,0.915, and 0.920 g/cm³. Densities are determined in a manner consistentwith ASTM D-1505, at room temperature, as with all other reciteddensities herein.

In addition, the ethylene-α-olefin copolymers according to suchembodiments may have a melt index within the range of about 0.4 g/10 minto about 40 g/10 min, or from about 0.5 g/10 min to about 30 g/10 min.Melt index of an ethylene-α-olefin copolymer according to certain ofthese embodiments falls within the range of any one of about 0.4, 0.5,0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, and 1.5 g/10 min to any oneof about 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20, 25, 30, 35,and 40 g/10 min. These MIs are, as elsewhere in this disclosure,determined in a manner consistent with ASTM D1238, at 190° C. and 2.16kg weight.

An ethylene-α-olefin of certain embodiments may be an ethylene-octenecopolymer having both a density falling within the range of about 0.865to about 0.900 g/cm³, and a MI falling within the range of about 0.5 toabout 4.0 g/10 min. The ethylene-α-olefin copolymer of other particularembodiments may be an ethylene-butene and/or an ethylene-hexenecopolymer having both a density falling within the range of about 0.870to about 0.910 g/cm³, and a MI falling within the range of about 1.0 toabout 30.0 g/10 min. And the ethylene-α-olefin copolymer of yet otherparticular embodiments may be an ethylene-octene copolymer having both adensity falling within the range of about 0.880 to about 0.910 g/cm³ anda MI falling within the range of about 1.0 to about 30.0 g/10 min.

Examples of suitable ethylene-α-olefin copolymers include Exact™ethylene-based copolymers commercially available from ExxonMobilChemical Company, Houston, Tex., including Exact™ ethylene-butenecopolymers and Exact™ ethylene-octene copolymers.

Ethylene-Propylene Rubber Carrier Resins

In some embodiments, the carrier resin may also or instead include oneor more ethylene-propylene rubbers (“EP rubbers”). Optionally, the EPrubber may include one or more diene-based monomers. For instance, theEP rubber of some embodiments may be an EPDM terpolymer.

The EP rubber of certain embodiments includes ethylene-based units in anamount greater than or equal to any one or more of about 45, 50, 55, 60,and 65 wt %, and in an amount less than or equal to any one or more ofabout 55, 60, 65, 70, 75, 80, and 85 wt %, by weight of the EP rubber,provided that the upper limit is greater than or equal to the lowerlimit.

The EP rubber may have diene content (e.g., amount of diene-derivedcomonomers) within the range of about 0 wt % to about 10.0 wt %, byweight of the EP rubber. In particular embodiments, the diene contentmay be greater than or equal to any one of about 0.0, 0.5, 1.0, 1.5,2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 wt %, and less than or equal toany one of about 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0,8.5, 9.0, 9.5, and 10.0 wt %, by weight of the EP rubber, provided theupper limit is greater than or equal to the lower limit.

In particular embodiments, the EP rubber may have a density within therange of about 0.850 to about 0.885 g/cm³, or from about 0.860 to about0.880 g/cm³. In addition, EP rubbers according to such embodiments mayhave a MI within the range of about 0.05 to about 1.1 g/10 min, or about0.1 to about 1.0 g/10 min. Density and MI are determined in a mannerconsistent with ASTM D-1505 (room temperature) and ASTM D-1238 (190° C.,2.16 kg), respectively.

Masterbatch Formation

Returning now to the masterbatch, it may be formed by any suitableprocess for blending one or more additive (e.g., carbon black) particleswith, and dispersing such particles in, a carrier resin. For instance,the additive particles and carrier resin may be dry blended and themixture subsequently melt-mixed at a temperature above the meltingtemperature of the carrier resin, either directly in an extruder used tomake the finished article, or by pre-melt mixing in a separate mixer(for example, a Banbury™ mixer). Dry blends of the masterbatch can alsobe directly injection molded without pre-melt mixture. Examples ofmachinery capable of generating the shear and mixing include extruderswith kneaders or mixing elements with one or more mixing tips orflights, extruders with one or more screws, extruders of co- orcounter-rotating type, a Coperion ZSK twin-screw extruder (availablefrom Coperion Corporation), a Banbury mixer, a FCM™ Farrell ContinuousMixer (both available from Farrel Corporation, Ansonia Conn.), a BUSSKneader™ (available from Buss, Inc. USA of Carol Stream, Ill.), and thelike. The type and intensity of mixing, temperature, and residence timerequired can be achieved by the choice of one of the above machines incombination with the selection of kneading or mixing elements, screwdesign, and screw speed (<3000 rpm). Typically the temperature formelt-mixing is from about 60° C. to about 130° C., and the residencetime is from about 10 to about 20 minutes.

Once melt-mixed or otherwise melt-blended, the masterbatch comprisingthe additive particles and propylene-α-olefin carrier resin may bepelletized by any suitable means, such as strand pelletization or thelike. In some embodiments, underwater pelletization (e.g., extrudingmolten masterbatch into a water bath maintained at a temperaturesubstantially lower than that of the molten extrudate, and pelletizingthe masterbatch) may be particularly suited to pelletizing themasterbatch, owing at least in part to the propylene-α-olefincopolymer's nature. In certain embodiments, underwater pelletizing ofthe masterbatch may be carried out according to the techniques taught inU.S. Pat. No. 8,709,315, the entirety of which is incorporated byreference herein.

The masterbatch according to some embodiments is blended and formed suchthat the carbon black and/or other additive particles are well-dispersedwithin the propylene- or ethylene-based copolymer carrier resin, and aresubstantially non-agglomerated therein.

In particular embodiments wherein the additive comprises carbon black,agglomeration of carbon black particles in the carrier resin may beavoided by capping the amount of carbon black included in the carrierresin. Advantageously, use of the propylene-α-olefin copolymer as thecarrier resin in accordance with certain embodiments may allow a largeramount of carbon black particles to be dispersed within the carrierresin, while still preventing agglomeration of those particles. Thisallows a greater amount of carbon black to be present in the TPVformulation, thereby reducing the cost of the formulation withoutadversely affecting the properties of the resulting TPV. For instance,with a greater carbon black loading in the masterbatch, less totalmasterbatch would be required to achieve the same ultimate concentrationin the resulting TPV, which results in lower transportation cost and thelike. However, even using a carrier resin according to embodiments ofthe present invention, carbon black particles will still agglomeratewhen present above a sufficiently high concentration, whichagglomeration could lead to insufficient mixing and/or surface defectsin the resulting TPV including the masterbatch. Thus in someembodiments, the masterbatch may comprise less than or equal to about 50wt % carbon black particles; in other embodiments, the masterbatch maycomprise less than or equal to any one of about 49, 48, 47, 46, 45, 44,and 43 wt % carbon black particles. In some embodiments, the masterbatchmay comprise greater than or equal to any one of 35, 36, 37, 38, 39, 40,41, 42, and 43 wt % carbon black particles. In certain embodiments, themasterbatch comprises about 45 wt % carbon black particles.

In some embodiments, the masterbatch further comprises one or moreadditional components (besides the one or more filler, pigmentation,extender, or other additives such as carbon black), such as any one ormore of processing aids (e.g., slip agents), antioxidants, stabilizers,and the like. In certain embodiments, any additive suitable forinclusion in a TPV (particulate or not) may be incorporated into themasterbatch.

Additional TPV Additives

The thermoplastic vulcanizate formulations of some embodiments mayoptionally further comprise one or more additives in addition to themasterbatch. Suitable additional TPV additives include, but are notlimited to, plasticizers, process oils, fillers, processing aids, acidscavengers, and/or the like.

Any suitable process oil may be included in the TPV formulation of someembodiments. In particular embodiments, process oils may be selectedfrom: (i) extension oil, that is, oil present in an oil-extended rubber(such as oil present in the elastomer component); (ii) free oil, thatis, oil that is added during the vulcanization process (separately fromany other TPV formulation component such as the elastomer andthermoplastic vulcanizate); (iii) curative oil, that is, oil that isused to dissolve/disperse the curative, for example, a curative-in-oildispersion such as a phenolic resin-in-oil (and in such embodiments, thecuring composition may therefore be present in the TPV formulation asthe curative-in-oil additive); and (iv) any combination of the foregoingoils from (i)-(iii). Thus, process oil is may be present in a TPVformulation as part of another component (e.g., as part of the elastomercomponent when the process oil is an extension oil, such that theelastomer component comprises elastomer and extension oil; or as part ofthe curing composition when the process oil is the carrier of acurative-in-oil, such that the curing composition comprises the curativeoil and a curing agent). On the other hand, process oil may be added tothe TPV separately from other components, i.e., as free oil.

The extension oil, free oil, and/or curative oil may be the same ordifferent oils in various embodiments. Process oils may include one ormore of (i) “refined” or “mineral” oils, and (ii) synthetic oils. Asused herein, mineral oils refer to any hydrocarbon liquid of lubricatingviscosity (i.e., a kinematic viscosity at 100° C. of 1 mm²/sec or more)derived from petroleum crude oil and subjected to one or more refiningand/or hydroprocessing steps (such as fractionation, hydrocracking,dewaxing, isomerization, and hydrofinishing) to purify and chemicallymodify the components to achieve a final set of properties. Such“refined” oils are in contrast to “synthetic” oils, which aremanufactured by combining monomer units into larger molecules usingcatalysts, initiators, and/or heat.

In general, either refined or synthetic process oils according to someembodiments may include, but are not limited to, any one or more ofaromatic, naphthenic, and paraffinic oils. Exemplary syntheticprocessing oils are polylinear alpha-olefins, polybranchedalpha-olefins, and hydrogenated polyalphaolefins. The compositions ofsome embodiments of this invention may include organic esters, alkylethers, or combinations thereof. U.S. Pat. No. 5,290,886 and U.S. Pat.No. 5,397,832 are incorporated herein in this regard.

In certain embodiments, at least a portion of the process oil (e.g., allor a portion of any one or more of extension oil, free oil, and/orcurative oil) is a low aromatic/sulfur content oil and has (i) anaromatic content of less than 5 wt %, or less than 3.5 wt %, or lessthan 1.5 wt %, based on the weight of that portion of the process oil;and (ii) a sulfur content of less than 0.3 wt %, or less than 0.003 wt%, based on the weight of that portion of the process oil. Aromaticcontent may be determined in a manner consistent with method ASTM D2007.The percentage of aromatic carbon in the process oil of some embodimentsis preferably less than 2, 1, or 0.5%. In certain embodiments, there areno aromatic carbons in the process oil. The proportion of aromaticcarbon (%) as used herein is the proportion (percentage) of the numberof aromatic carbon atoms to the number of all carbon atoms determined bythe method in accordance with ASTM D2140.

Suitable process oils of particular embodiments may include API Group I,II, III, IV, and V base oils. See API 1509, Engine Oil Licensing andCertification System, 17^(th) Ed., September 2012, Appx. E, incorporatedherein by reference. Particular examples of suitable process oilsinclude Paralux™ and/or Paramount™ oils commercially available fromChevron Corp., Houston, Tex.

In general, suitable process oils may include any process oil describedin U.S. Provisional Patent Application No. 61/992,020, entitled“Thermoplastic Vulcanizates and Method of Making the Same,” filed May12, 2014, the entirety of which is incorporated herein by reference.Further, process oils of some embodiments may be present in anyproportion(s) described therein.

A TPV formulation of some embodiments may also or instead include apolymeric processing additive. The processing additive employed in suchembodiments is a polymeric resin that has a very high melt flow index.These polymeric resins include both linear and branched molecules thathave a melt flow rate that is greater than about 500 dg/min, morepreferably greater than about 750 dg/min, even more preferably greaterthan about 1000 dg/min, still more preferably greater than about 1200dg/min, and still more preferably greater than about 1500 dg/min. Thethermoplastic elastomers of the present invention may include mixturesof various branched or various linear polymeric processing additives, aswell as mixtures of both linear and branched polymeric processingadditives. Reference to polymeric processing additives will include bothlinear and branched additives unless otherwise specified. The preferredlinear polymeric processing additives are polypropylene homopolymers.The preferred branched polymeric processing additives includediene-modified polypropylene polymers. Thermoplastic vulcanizates thatinclude similar processing additives are disclosed in U.S. Pat. No.6,451,915, which is incorporated herein by reference.

In addition, the formulation may also or instead include reinforcing andnon-reinforcing fillers, antioxidants, stabilizers, lubricants,antiblocking agents, anti-static agents, waxes, foaming agents,pigments, flame retardants and other processing aids known in the rubbercompounding art. These additives can comprise up to about 50 weightpercent of the total composition in certain embodiments. Fillers andextenders that can be utilized include conventional inorganics such ascalcium carbonate, clays, silica, talc, titanium dioxide, as well asorganic and inorganic nanoscopic fillers. Fillers are preferably addedin masterbatch form, in combination with a carrier resin such aspolypropylene.

In certain embodiments, additional TPV additives may be added in theirown separate additional masterbatch(es) (e.g., with one or moreadditional TPV additives per such additional masterbatch). In suchembodiments, each additional masterbatch may comprise a carrier resinaccording to the carrier resin of any of the masterbatches of variousembodiments discussed above, and/or it may comprise a conventionalcarrier resin.

In certain embodiments, the TPV formulation may include acid scavengers.These acid scavengers are preferably added to the thermoplasticvulcanizates after the desired level of cure has been achieved(discussed in greater detail below with respect to processing TPVformulations). Preferably, the acid scavengers are added after dynamicvulcanization. Useful acid scavengers include hydrotalcites. Bothsynthetic and natural hydrotalcites can be used. An exemplary naturalhydrotalcite can be represented by the formula Mg₆Al₂(OH)₁₋₆CO₃.4H₂O.Synthetic hydrotalcite compounds, which are believed to have theformula: Mg_(4.3)Al₂(OH)_(12.6)CO₃.mH₂O orMg_(4.5)Al₂(OH)₁₃CO_(3.3).5H₂O, can be obtained under the tradenamesDHT-4A™ or Kyowaad™ 1000 (Kyowa; Japan). Another commercial example isthat available under the trade name Alcamizer™ (Kyowa).

Compositions of TPV Formulations

In general, a TPV formulation according to various embodiments includesthe elastomer component, thermoplastic resin, curing agent, andmasterbatch (e.g., carbon black masterbatch), along with any otheroptional additives. As will be discussed in more detail below, the TPVformulation undergoes processing, including dynamic vulcanization, toform a TPV. In certain embodiments, the masterbatch and/or any otheradditives may be added to the TPV formulation during processing, eitherbefore or after dynamic vulcanization.

Relative amounts of the various components in TPV formulations areconveniently characterized based upon the amount of elastomer in theformulation, in particular in parts by weight per hundred parts byweight of rubber (phr). In embodiments wherein the elastomer componentcomprises both elastomer and extension oil, as is common for muchcommercially available elastomers such as EPDM, the phr amounts arebased only upon the amount of elastomer in the elastomer component,exclusive of extension oil present in the elastomer component. Thus, anelastomer component containing 100 parts EPDM (rubber) and 75 partsextension oil would in fact be considered present in a TPV formulationat 175 phr (i.e., on the basis of the 100 parts EPDM rubber). If such aTPV formulation were further characterized as containing 50 phrthermoplastic resin, the formulation would include 50 parts by weight ofthermoplastic resin in addition to the 100 parts by weight elastomer and75 parts by weight extension oil.

TPV formulations of some embodiments may include the thermoplastic resinin an amount from about 20 to about 300 parts per hundred parts byweight of the elastomer or rubber (phr). In various embodiments, thethermoplastic resin is included in a TPV formulation in an amountranging from a low of any one of about 30, 35, 40, 45, 50, 55, 60, 65,70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140,145, 150, 165, 170, and 175 phr, to a high of any one of about 100, 125,150, 175, 200, 225, 250, 275, and 300 phr. The thermoplastic resin maybe included in an amount ranging from any of the aforementioned lows toany of the aforementioned highs, provided that the high value is greaterthan or equal to the low value. In particular embodiments, increasingamounts of thermoplastic resin correspond to increasing hardness of thedynamically vulcanized TPV.

When the elastomeric component consists of elastomer only, it is bydefinition present at 100 phr (since it is the basis of the phrnotation). However, in embodiments wherein the elastomeric componentcomprises a constituent other than an elastomer, such as an extenderoil, the elastomeric component may be included in a TPV formulation inan amount ranging from a low of any one of about 100.05, 100.1, 100.15,100.2, 105, 110, 115, and 120 phr to a high of any one of about 110,120, 125, 150, 175, 200, 225, and 250 phr.

TPV formulations of various embodiments further comprise masterbatch(comprising an additive (e.g., carbon black) and carrier resincomprising propylene- or ethylene-based copolymer) in an amount rangingfrom a low of any one of about 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,15, 16, 17, 18, 19, 20, 21, 22, 23, 24, and 25 phr, to a high of any oneof about 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,49, and 50 phr. The masterbatch may be included in an amount rangingfrom any one of the aforementioned lows to any one of the aforementionedhighs, provided that the high value is greater than or equal to the lowvalue. In certain embodiments in which multiple additives (particulateand/or otherwise) are included in the masterbatch, the masterbatch maybe present in the TPV formulation in higher amounts, such as up to anyone of about 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 150, 200, 250,300, and 350 phr.

The TPV formulations also include one or more curing compositions (thecuring composition, as discussed above, comprising curing agent andoptionally one or more coagents and/or curative oils). In someembodiments, the one or more curing compositions are present in a TPVformulation in an aggregate amount ranging from a low of any one ofabout 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, and 10 phr to a high of anyone of about 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,19, 20, 21, 22, 23, 24, and 25 phr. The one or more curing agents may beincluded in an amount ranging from any one of the aforementioned lows toany one of the aforementioned highs, provided that the high value isgreater than or equal to the low value.

As previously noted, TPV formulations of certain embodiments mayoptionally include additional TPV additives, i.e., additives other thanto the one or more additives delivered in the masterbatch, and alsoother than any additives included in another component of the TPVformulation (such as the elastomer component). Amounts of additionaladditive are separate and in addition to those additives alreadyincluded in another component of a TPV formulation. For instance, anyadditive such as extension oil included in the elastomeric component hasalready been accounted for as part of the amount of elastomericcomponent added to the formulation; recited amounts of additionaladditives therefore are exclusive of additives already included in theelastomeric component. Similarly, any additive included in themasterbatch has also already been accounted for; accordingly, referenceherein to amounts of additional additive(s) do not include suchadditives already included in the masterbatch. Subject to the foregoingcaveats, additional additives may be present in a TPV formulation in theaggregate in an amount ranging from about 0 phr to about 300 phr. Incertain embodiments, additional additives may in the aggregate bepresent in the TPV in an amount ranging from a low of any one of about0, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 phr, to a high of any oneof about 100, 125, 150, 175, 200, 225, 250, 275, and 300 phr. Theadditional additives may be included in an aggregate amount ranging fromany one of the aforementioned lows to any one of the aforementionedhighs, provided that the high value is greater than or equal to the lowvalue.

For convenience, components of TPV formulations of various embodimentsmay alternatively be characterized based upon their weight percentagesin the TPV formulation according to the following:

-   -   The thermoplastic resin(s) may be present in a TPV formulation        in amounts ranging from a low of any one of about 5, 6, 7, 8, 9,        10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, and        25 wt % to a high of any one of about 12, 13, 14, 15, 16, 17,        18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33,        34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49,        50, 51, 52, 53, 54, and 55 wt %, provided that the high is        greater than or equal to the low.    -   The elastomeric component(s) may be present in a TPV formulation        in amounts ranging from a low of any one of about 3, 4, 5, 6, 7,        8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, and 35        wt % to a high of any one of about 35, 40, 45, 50, 55, 60, 65,        70, 75, and 80 wt %, provided that the high is greater than or        equal to the low, and that the elastomeric component(s) are        present in the TPV formulation within the range of about 20 to        about 300 phr.    -   The curative(s) may be present in a TPV formulation in amounts        ranging from a low of any one of about 0.4, 0.5, 0.6, 0.7, 0.8,        0.9, and 1.0 wt % to a high of any one of about 1.0, 1.5, 2, 3,        4, 5, 6, 7, 8, 9, 10, 11, 12, and 13 wt %, provided that the        high is greater than or equal to the low, and that the        curative(s) are present in the TPV formulation with the range of        about 0.5 to about 25 phr.    -   The masterbatch may be present in a TPV formulation in amounts        ranging from a low of any one of about 0.1, 0.5, 1, 2, 3, 4, 5,        6, 7, 8, 9, and 10 wt % to a high of any one of about 5, 6, 7,        8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,        24, 25, 26, 27, and 27.5 wt %, provided that the high is greater        than or equal to the low, and that the carbon black masterbatch        is present in the TPV formulation within the range of about 10        to about 50 phr. Where multiple additives are present in the        masterbatch in accordance with the previous discussion, the        masterbatch may be present in amounts up to any one of about 30,        35, 40, 45, 50, 55, and 60 wt %, provided the carbon black        masterbatch is present in the TPV formulation within the range        of about 10 to about 350 phr.    -   The optional additional TPV additive(s) may be present in a TPV        formulation in aggregate amounts ranging from a low of any one        of about 0, 5, 10, 15, 20, 25, 30, 35, and 40 wt % to a high of        any one of about 30, 35, 40, 45, 50, 55, 60, and 65 wt %,        provided that the high is greater than or equal to the low, and        that the additive(s) are present in the TPV formulation within        the range of about 0 to about 300 phr.

Finally, it should also be noted that, in certain embodiments, theamount of propylene-α-olefin copolymer present in the TPV formulation(added through the carbon black masterbatch, other additivemasterbatch(es), and/or through any other means) is in aggregate lessthan or equal to any one of about 6, 5, 4, 3, or 2 wt %, by total weightof the TPV formulation. In certain preferred embodiments, thepropylene-α-olefin copolymer may be present in the TPV formulationand/or the resulting TPV in an amount less than about 4 wt %, and inother embodiments less than or equal to about 3 wt %.

Processing TPV Formulations

The thermoplastic vulcanizates are preferably prepared by processing ofthe TPV formulation, which processing according to some embodimentsincludes dynamic vulcanization. Dynamic vulcanization refers to avulcanization (i.e., cross-linking or curing) process for an elastomercontained in a blend that includes the elastomer, curatives, and atleast one thermoplastic resin. The elastomer is vulcanized underconditions of shear and extension at a temperature at or above themelting point of the thermoplastic resin. The elastomer is thussimultaneously crosslinked and dispersed (preferably as fine particles)within the thermoplastic resin matrix, although other morphologies, suchas co-continuous morphologies, may exist depending on the degree ofcure, the elastomer to plastic viscosity ratio, the intensity of mixing,the residence time, and the temperature.

In some embodiments, processing may include melt blending, in a chamber,a TPV formulation comprising the elastomer component, thermoplasticresin, and curing agent. The chamber may be any vessel that is suitablefor blending the selected composition under temperature and shearingforce conditions necessary to form a thermoplastic vulcanizate. In thisrespect, the chamber may be a mixer, such as a Banbury™ mixer, or amill, or an extruder. According to one embodiment, the chamber is anextruder, which may be a single or multi-screw extruder. The term“multi-screw extruder” means an extruder having two or more screws; withtwo and three screw extruders being exemplary, and two or twin screwextruders being preferred in some embodiments. The screws of theextruder may have a plurality of lobes; two and three lobe screws beingpreferred. It will readily be understood that other screw designs may beselected in accordance with the methods of embodiments of the presentinvention. In some embodiments, dynamic vulcanization may occur duringand/or as a result of extrusion.

The dynamic vulcanization of the elastomer may be carried out so as toachieve relatively high shear as defined in U.S. Pat. No. 4,594,390,which is incorporated herein by reference. In some embodiments, themixing intensity and residence time experienced by the ingredientsduring dynamic vulcanization is preferably greater than that proposed inU.S. Pat. No. 4,594,390. In particular embodiments, the blending may beperformed at a temperature not exceeding about 400° C., preferably notexceeding about 300° C., and more preferably not exceeding about 250° C.The minimum temperature at which the melt blending is performed isgenerally higher than or equal to about 130° C., preferably higher thanor equal to about 150° C. and more particularly higher than about 180°C. The blending time is chosen by taking into account the nature of thecompounds used in the TPV formulation and the blending temperature. Thetime generally varies from about 5 seconds to about 120 minutes, and inmost cases from about 10 seconds to about 30 minutes.

Dynamic vulcanization in some embodiments may include phase inversion.As those skilled in the art appreciate, dynamic vulcanization may beginby including a greater volume fraction of rubber than thermoplasticresin. As such, the thermoplastic resin may be present as thediscontinuous phase when the rubber volume fraction is greater than thatof the volume fraction of the thermoplastic resin. As dynamicvulcanization proceeds, the viscosity of the rubber increases and phaseinversion occurs under dynamic mixing. In other words, upon phaseinversion, the thermoplastic resin phase becomes the continuous phase.

Carbon black masterbatch and any other additive(s) are preferablypresent within the TPV formulation when dynamic vulcanization is carriedout, although in some embodiments, masterbatch and/or any one or moreother additives (if any) may be added to the composition after thecuring and/or phase inversion (e.g., after the dynamic vulcanizationportion of processing). Masterbatch and/or other additional ingredientsmay be included after dynamic vulcanization by employing a variety oftechniques. In one embodiment, the masterbatch and/or other additionalingredients can be added while the thermoplastic vulcanizate remains inits molten state from the dynamic vulcanization process. For example,the additional ingredients can be added downstream of the location ofdynamic vulcanization within a process that employs continuousprocessing equipment, such as a single or twin screw extruder. In otherembodiments, the thermoplastic vulcanizate can be “worked-up” orpelletized, subsequently melted, and the additional ingredients can beadded to the molten thermoplastic vulcanizate product. This latterprocess may be referred to as a “second pass” addition of theingredients.

In certain embodiments, the TPV in molten form may be passed through ascreen pack comprising one or more mesh screens at any point afterdynamic vulcanization. The screen pack in certain embodiments comprisesa 200 Standard U.S. Mesh screen (i.e., a mesh screen having 200 openingsas measured across one linear inch of the mesh), or a finer screen(i.e., a screen having a larger number of openings in one inch than a200 mesh screen, such as a 230, 270, 325, or 400 U.S. Mesh screen). Inother embodiments, the screen pack may comprise a 120, 140, 170, orfiner U.S. Mesh screen. The screen pack of certain embodiments comprisesmultiple screens. For instance, the screen pack may comprise threescreens in series: an inner mesh screen that is the most refined screensandwiched between two supporting screens (e.g., via edge welding orother conventional means of forming a screen pack). For example, thescreen pack may be a 20/200/20 pack (referencing a 200 U.S. Mesh screensandwiched between two 20 U.S. Mesh screens). In other embodiments, thescreen pack may include 5, or more than 5, screens in series, such as a10/20/200/20/10 screen arrangement (with the numbers again referencingU.S. Mesh sizes). In general, the center-most screen may be the mostrefined screen in the screen pack, surrounded by 2 or more supportingscreens in series. The supporting screens may be any suitable mesh sizethat is less refined than the center screen (e.g., any one of 20, 25,30, 35, 40, 45, 50, 60, 70, 80, 100, etc. U.S. Mesh). Mesh sizes in ascreen may equivalently be represented in microns, where the number ofmicrons indicates the width or length of an approximately square openingin the screen. Thus, a 200 U.S. Mesh screen (having 200 openings asmeasured across one linear inch of the mesh) is equivalent to a 74micron screen (meaning each approximately square opening has length andwidth of 74 microns).

In some such embodiments, the TPV may be passed through the screen packdirectly after dynamic vulcanization, or in other embodiments, it may bepassed through the screen pack at any other point in which thecomposition is in a molten state (e.g., during a second pass addition ofother ingredients). Advantageously, passing the TPV through such ascreen pack according to some embodiments may enhance surface smoothnessof the resulting TPV after extrusion or other processing.

Despite the fact that the elastomer may be partially or fully cured, thecompositions of this invention can be processed and reprocessed byconventional plastic processing techniques such as extrusion, injectionmolding, and compression molding. The rubber within these thermoplasticelastomers is usually in the form of finely-divided and well-dispersedparticles of vulcanized or cured rubber within a continuousthermoplastic phase or matrix, although a co-continuous morphology or aphase inversion is also possible.

Inclusion of the propylene- or ethylene-based copolymer as a masterbatchcarrier resin increases the TPV formulation's processability (and/or theTPV's processability) in some embodiments. For instance, TPVsformulations formed according to some embodiments exhibit increasedextrusion throughput, in particular as compared to TPV formulationsformed from masterbatches using conventional carrier resins such ashomopolypropylene. This extrusion throughput increase may be realized ineither or both of: original processing of the TPV formulation to formthe TPV, and/or in processing of the formed TPV (e.g., reprocessing ofTPV pellets or the like for end-use product formation, discussed in moredetail below). Extrusion throughput of TPV formulations comprisingpropylene- or ethylene-based copolymer carrier resins according to someembodiments may be about 2% to about 15% greater than extrusionthroughput rates for corresponding TPV formulations instead comprisinghomopolypropylene or other conventional carrier resins. In certainembodiments, the improvement may be about 5% to about 7%.

Resulting Thermoplastic Vulcanizate

The resulting TPV in some embodiments may accordingly be characterizedas comprising the compounded reaction product of the ingredients formingthe TPV formulation following processing of those ingredients, whereinthe processing includes dynamic vulcanization.

In preferred embodiments, the TPV comprises the cured elastomer in theform of finely-divided and well-dispersed particles within thethermoplastic medium. Put another way, the TPV comprises a dispersephase (comprising the at least partially cured elastomer component) in acontinuous phase (comprising the thermoplastic resin). In various ofthese embodiments, the elastomer particles have an average diameter thatis less than 50 micrometers, preferably less than 30 micrometers, evenmore preferably less than 10 micrometers, still more preferably lessthan 5 micrometers and even more preferably less than 1 micrometer. Inpreferred embodiments, at least 50%, more preferably at least 60%, andeven more preferably at least 75% of the particles have an averagediameter of less than 5 micrometers, more preferably less than 2micrometers, and even more preferably less than 1 micrometer.

In one embodiment, the elastomer in the resulting TPV is advantageouslycompletely or fully cured. The degree of cure can be measured bydetermining the amount of rubber that is extractable from thethermoplastic vulcanizate by using boiling xylene as an extractant. Thismethod is disclosed in U.S. Pat. No. 4,311,628, which is incorporatedherein by reference. Preferably, the rubber has a degree of cure wherenot more than 15 weight percent, preferably not more than 10 weightpercent, more preferably not more than 5 weight percent, and still morepreferably not more than 3 weight percent is extractable by boilingxylene as described in U.S. Pat. Nos. 5,100,947 and 5,157,081, which areincorporated herein by reference. Alternatively, the rubber has a degreeof cure such that the crosslink density is preferably at least 4×10⁻⁵,more preferably at least 7×10⁻⁵, and still more preferably at least10×10⁻⁵ moles per milliliter of elastomer. See also “Crosslink Densitiesand Phase Morphologies in Dynamically Vulcanized TPEs,” by Ellul et al.,68 RUBBER CHEMISTRY AND TECHNOLOGY pp. 573-584 (1995), incorporatedherein by reference.

Incorporation of the propylene-α-olefin copolymer as a carrier resin ofthe masterbatch surprisingly results in improved properties of the TPV,such as surface smoothness. As will be discussed in greater detail inconnection with the Examples below, this is unexpected as compared toTPVs formed from inclusion of even the same propylene-α-olefin copolymervia direct blending of the propylene-α-olefin into a TPV formulation (asopposed to inclusion of the propylene-α-olefin copolymer as the carrierresin of the included carbon black masterbatch). This is because it hasbeen found generally that increasing amounts propylene-α-olefincopolymer included in a TPV formulation result in increased throughputof the TPV during processing steps such as extrusion, but at thetradeoff of negatively impacting the elastic properties of the resultantTPV. In particular, the minimum amount of propylene-α-olefin copolymerdirectly blended into a TPV formulation that is necessary for improvedextrusion throughput rates is at least 6 wt %, by weight of the finalTPV. However, including propylene-α-olefin copolymer in the TPV beyond 4wt % adversely affects the TPV's elastic properties, such as the TPV'scompression set (i.e., the TPV's permanent deformation resulting fromapplication of a force to the TPV, after removal of the force).

Surprisingly, using the propylene-α-olefin copolymer as a carrier resinin the carbon black masterbatch, and adding such a carbon blackmasterbatch to the TPV, allows the throughput benefits to be realized atless than 4 wt %, such as at only about 3 wt %, total propylene-α-olefincopolymer in the TPV (as shown in Samples E1 and E2 of Example 2 below).This is advantageously below the cut-off of 4 wt % propylene-α-olefincopolymer, above which elastomeric properties of the TPV decline.

As with TPV formulations, the extrusion throughput rate of the resultingTPV (e.g., when TPV pellets or the like are reprocessed for end-useproduct formation) is also enhanced in some embodiments, as compared toextrusion throughput of TPVs formed with conventional carrier resinssuch as homopolypropylene. Extrusion throughput of TPVs comprisingpropylene- or ethylene-based copolymer carrier resins according to someembodiments may be about 2% to about 15% greater than extrusionthroughput rates for corresponding TPVs instead incorporatingmasterbatch(es) of homopolypropylene and/or other conventional carrierresins. In certain embodiments, the improvement may be about 5% to about7%.

Further, propylene-α-olefin copolymer included in such a manneradditionally enhances surface appearance of the final TPV. The improvedsurface appearance is observed as either decreased extrusion surfaceroughness (ESR), surface spot count, or both. Extrusion surfaceroughness is a measure of surface texture as described in ChemicalSurface Treatments of Natural Rubber And EPDM Thermoplastic Elastomers:Effects on Friction and Adhesion, Rubber Chemistry and Technology, Vol.67, No. 4 (1994), which is incorporated herein by reference. Surfacespot count is a visual measure of the number of surface spots on anextruded thermoplastic vulcanizate sample. As reported herein, surfacespot counts and ESR values are based upon a 1 in.×18 in. extruded TPVstrip. Surface spot counts are performed by visual inspection, andinvolve counting the number of blemishes (e.g., topographicalunevenness, discoloration, or other irregularity visible to the nakedhuman eye, as opposed to visible through microscopy). ESR is measured inmicrons according to R_(a), the arithmetic average of the roughnessprofile.

A TPV of certain embodiments (and/or a TPV formed by certainembodiments) may have a surface spot count less than or equal to any oneof 9, 8, 7, 6, 5, 4, 3, 2, or 1.

EXAMPLES Example 1

Four carbon black masterbatches were prepared with different carrierresins to make TPVs as shown in Table 1. First, three carbon blackmasterbatch samples (#1-3) were made of commercially available isotacticpolypropylene carrier resins of different MFR (as reported in Table 1),and the fourth masterbatch sample was made with a carrier resin of apropylene-α-olefin copolymer in accordance with the propylene-α-olefincopolymers of embodiments discussed above (in this case, Vistamaxx™polymer, grade 6202, available from ExxonMobil Chemical Company,Baytown, Tex.). The Vistamaxx™ polymer, grade 6202, had a density of0.863 g/cm³ as determined in accordance with ASTM D1505; melt index of9.1 g/10 min as determined according to ASTM D1238 (at 190° C., 2.16kg); a melt flow rate (MFR) of 20 g/10 min; and ethylene-derived unitcontent of 15 wt % (the balance being propylene-derived units). Theisotactic polypropylene homopolymers (of samples #1-3) had typicalisotactic polypropylene densities of 0.945 g/cm³.

The concentration of carbon black in the masterbatch was kept at 40 wt %for the polypropylene resins due to agglomeration taking place in highercarbon black concentrations; however, the carbon black in sample #4(using the Vistamaxx™ 6202 as carrier resin) was present at 45 wt %.

TABLE 1 Carbon Black Masterbatch Samples Masterbatch (MB) Sample #1 #2#3 #4 Carbon Black in 40 40 40 45 MB (wt %) 35 MFR PP in 60 — — — MB (wt%) 12 MFR PP in — 60 — — MB (wt %) 10 MFR PP in — — 60 — MB (wt %)VM6202 (wt %) — — — 55

Example 2

Each of the carbon black masterbatches from Example 1 was used to maketwo TPV formulations, for a total of 8 sample formulations. Each TPVformulation was formed into pellets using a Coperion ZSK53 twin-screwextruder operated at about 300 RPM. Production rate was about 90 kg/hr.At the end of the twin-screw extruder, prior to formation of the finalpellet, the material was passed through a screen pack comprising eithera 100 U.S. Mesh or 200 U.S. Mesh screen (20/100/20 and 20/200/20 screenpacks, respectively). Thus, four of the samples (C1, C3, C5, and E1)were made using 100 U.S. Mesh, and four (C2, C4, C6, and E2) with 200U.S. Mesh. The eight TPV formulations, and properties of each of theeight resulting TPVs, are given below in Table 2 as samples C1-C6 andE1-E2, with each of E1 and E2 indicating the inventive TPV formulationsincluding the Masterbatch Sample #4 from Example 1 (i.e., themasterbatch including propylene-α-olefin carrier resin). In addition,Table 2 also includes sample C8, which was prepared by directly addingpropylene-α-olefin copolymer (Vistamaxx™ 3000) to the TPV formulation.Sample C7 is a second sample prepared using Carbon Black MB #1 fromExample 1 above, given as further comparison against C8.

The extrusion throughput rates of Table 2 are reported for asingle-screw extruder, indicating the throughput rate of the TPV pelletswhen the TPV pellets are processed in a single-screw extruder (e.g., forend-use TPV product formation).

As shown in Table 2, each sample TPV formulation further includedvarious other ingredients. “EPDM” was Vistalon™ 3666 EPDM rubber whichis an ethylene-propylene-diene rubber that has 64.0 wt % ethylenecontent (ASTM D3900) and 4.5 wt % ENB diene content (ASTM D6047). V3666is oil extended with 75 phr of oil and has a Mooney Viscosity of 52 MU(ML 1+4, 125° C.; ASTM D1646). V3666 is commercially available fromExxonMobil Chemical Company.

“Clay” was Icecap™ K Clay.

“Zinc Oxide” or “ZnO” was Kadox 911 zinc oxide.

“FRPP” was low melt or fractional melt polypropylene homopolymer PP5341,commercially available from ExxonMobil Chemical Company. HFPP was highflow polypropylene homopolymer F180A, commercially available fromBraskem America, Inc. The FRPP and HFPP together constitute thethermoplastic resin of the TPV formulation.

“SnCl₂” was an anhydrous stannous chloride polypropylene masterbatch.The stannous chloride masterbatch contained 45 wt % stannous chlorideand 55 wt % of polypropylene having an MFR of 0.8 g/10 min.

“RIO” was a phenolic resin-in-oil curative that contained 30 wt %phenolic resin and 70 wt % process oil.

“Oil #1” and “Oil #2” were each Paralux™ 6001R oil, which iscommercially available from Chevron Corporation. Oil #1 and Oil #2 wererespectively added to the formulation at different points along theCoperion extruder before and after dynamic vulcanization.

“VM3000” was Vistamaxx™ polymer, grade 3000, commercially available fromExxonMobil Chemical Company. VM3000 had density of 0.873 g/cm³ (measuredaccording to ASTM D1505), MI 3.6 g/10 min (ASTM D1238, at 190° C., 2.16kg), MFR of 8 g/10 min, 11 wt % ethylene-derived units and the balancepropylene-derived units.

Carbon Black MB #1-#4 each respectively indicate one of the Carbon BlackMasterbatches prepared as set forth in Example 1.

TABLE 2 Sample TPV Properties C1 C3 C5 E1 C2 C4 C6 E2 C7 C8 EPDM (phr)175 175 175 175 175 175 175 175 175 175 Clay (phr) 42 42 42 42 42 42 4242 42 42 ZnO (phr) 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 2 2 FRPP (phr) 28.9228.92 28.92 29.99 28.92 28.92 28.92 29.99 38.34 38.34 HFPP (phr) 10.810.8 10.8 12.4 10.8 10.8 10.8 12.4 0 0 SnCl₂ (phr) 1.67 1.67 1.67 1.671.67 1.67 1.67 1.67 1.67 1.67 Oil#1 (phr) 5.82 5.82 5.82 5.82 5.82 5.825.82 5.82 10.82 10.82 RIO (phr) 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 10.2910.29 Oil#2 (phr) 52.33 52.33 52.33 52.33 52.33 52.33 52.33 52.33 43.3VM3000 (phr) 14.49 Carbon Black MB #1 24 24 24.25 24.25 Carbon Black MB#2 24 24 Carbon Black MB #3 24 24 Carbon Black MB #4 21.3 21.3 MeltScreen Mesh 100 100 100 100 200 200 200 200 100 100 Size Single Screw68.04 67.08 66.96 78.6 69.48 68.88 63.6 78.72 72.4 74.4 Extruder Rate(Kg/hr) Extrudate Surface 10.00 15.00 10 8.00 9.00 3.00 6 2.00 — — SpotCounts Other Properties Specific Gravity (ISO 0.9625 0.9711 0.97770.9584 0.9674 0.97 0.9708 0.9746 1183-1, Method A) Hardness, Shore A69.4 73.6 74.4 69.1 73.2 73.2 73.6 72.2 72.4 73 (ISO 868 Plied - 15 sec.Delay) LCR Viscosity* Pa · S 78.7 80.1 88.8 76.8 93.2 78.2 78.5 TensionSet (%) 1.5 1 2 2 2 1 1.5 1.5 UTS, Mpa (ISO37, 6 6.9 6.6 6.1 6.6 6.7 6.56.2 7.23 7.49 Type 1, 500 mm/min Perpendicular to flow) M100, Mpa(ISO37, 2.94 3.22 3.25 2.75 3.09 3.21 3.14 3.07 3.29 3.28 Type 1, 500mm/min Perpendicular to flow) UE, % (ISO37, Type 430 440 440 420 450 420440 410 420 464 1, 500 mm/min Perpendicular to flow) ESR, Ra (micron)39.5 52.4 39.8 61.1 37.8 42.8 47.8 44.8 44 33 *LCR capillary viscositywas determined with a Dynisco ™ capillary rheometer at 30:1 L/D at 12001/s.

As shown in Table 2, the pelletized samples E1 and E2 in accordance withembodiments of the present invention exhibited superior extrusionthroughput rates (78.6 and 78.72 kg/hr single screw extruder rates,respectively) as compared to all other samples (including those preparedwith Vistamaxx™ added directly to the TPV formulation). In addition, thesurface spot counts of each of E1 and E2 were lower (i.e., the surfacesmoothness was higher) than the comparative TPV formulations made usingmasterbatches with polypropylene carrier resins (when comparing to othersamples made using the same screen size). Finally, as is also apparent,the 200 mesh screen resulted in lower surface spot counts across allsamples as compared to the same TPV formulation passed through a100-mesh screen.

The FIGURE further demonstrates the throughput rate improvement achievedthrough use of the propylene-α-olefin copolymer carbon black masterbatchcarrier resin. As shown in the FIGURE, Sample E1 significantlyoutperformed sample C1 and C7 (both made using conventional carbon blackmasterbatches), and furthermore outperformed sample C8 (made usingconventional carbon black masterbatch, and further with direct additionof Vistamaxx™ 3000 to the TPV formulation).

EMBODIMENTS Embodiment 1

A method comprising: introducing to a chamber each of a thermoplasticresin, an elastomer component, a curing agent, and a carbon blackmasterbatch; and dynamically vulcanizing at least a portion of theelastomer component so as to form a thermoplastic vulcanizate whereinthe elastomer component is at least partially vulcanized and isdispersed in a continuous phase comprising the thermoplastic resin;wherein the carbon black masterbatch comprises carbon black particlesdispersed in a carrier resin comprising a propylene- or ethylene-basedcopolymer having (i) a density between about 0.850 and about 0.920 g/cm³and (ii) a melt index between about 0.05 and about 50 g/10 min asdetermined in accordance with ASTM D1238, at 190° C. and 2.16 kg weight.

Embodiment 2

The method of Embodiment 1, further comprising: passing thethermoplastic vulcanizate through a 200 U.S. Mesh or finer screen, aftersaid dynamic vulcanization of the at least a portion of the elastomercomponent.

Embodiment 3

The method of any one of the foregoing embodiments, further comprisingmelt-mixing the propylene- or ethylene-based copolymer and the carbonblack particles, and forming a plurality of masterbatch pelletscomprising the carbon black particles dispersed in the propylene- orethylene-based copolymer carrier resin, such that the masterbatchpellets are used as the carbon black masterbatch thereafter introducedto the chamber.

Embodiment 4

The method of Embodiment 3 wherein forming the plurality of masterbatchpellets comprises underwater pelletizing the melt-mixed propylene- orethylene-based copolymer and carbon black particles.

Embodiment 5

The method of any one of the foregoing Embodiments, wherein the chamberis selected from the group consisting of a mixer, a mill, and anextruder.

Embodiment 6

The method of any one of the foregoing Embodiments, wherein the dynamicvulcanization is carried out at least in part by melt mixing thethermoplastic resin, the elastomer component, the curing agent, and thecarbon black masterbatch.

Embodiment 7

The method of any one of the foregoing Embodiments, wherein thepropylene- or ethylene-based copolymer is selected from the groupconsisting of propylene-α-olefin copolymers; ethylene-α-olefincopolymers; EP rubbers; and any combination thereof.

Embodiment 8

The method of Embodiment 7, wherein the propylene- or ethylene-basedcopolymer is a propylene-α-olefin copolymer comprising about 50 wt % toabout 99 wt % propylene-derived units and about 1 wt % to about 35 wt %comonomer units derived from one of ethylene and a C₄-C₁₀ alpha-olefin,and having a heat of fusion of about 75 J/g or less.

Embodiment 9

The method of Embodiment 8, wherein the thermoplastic vulcanizatecomprises less than or equal to 4 wt % of the propylene-α-olefincopolymer, by weight of the thermoplastic vulcanizate.

Embodiment 10

The method of Embodiment 7, wherein the propylene- or ethylene-basedcopolymer is an ethylene-α-olefin copolymer comprising about 60 wt % toabout 99 wt % ethylene-derived units and about 1 wt % to about 40 wt %comonomer derived units derived from one of butane and octene.

Embodiment 11

The method of Embodiment 7, wherein the propylene- or ethylene-basedcopolymer is an EP rubber comprising between about 45 wt % and about 85wt % ethylene-derived units and between about 0.5 wt % and about 10.0 wt% diene-derived comonomers.

Embodiment 12

The method of any one of the foregoing Embodiments, wherein theelastomer component comprises an ethylene-propylene-diene elastomer(EPDM).

Embodiment 13

The method of any one of the foregoing Embodiments, further comprisingintroducing to the chamber one or more additives selected from the groupconsisting of plasticizers, process oils, fillers, processing aids, acidscavengers, and any combination thereof.

Embodiment 14

A method for preparing a thermoplastic vulcanizate, the methodcomprising: (i) dynamically vulcanizing at least a portion of anelastomer component in the presence of a thermoplastic resin and acuring agent so as to form a thermoplastic vulcanizate wherein theelastomer component is at least partially vulcanized and is dispersed ina continuous phase comprising the thermoplastic resin; and (ii)introducing a carbon black masterbatch into the thermoplasticvulcanizate, wherein the carbon black masterbatch comprises carbon blackparticulates dispersed in a carrier resin comprising apropylene-α-olefin copolymer, the propylene-α-olefin copolymercomprising about 50 wt % to about 99 wt % propylene-derived units andabout 1 wt % to about 35 wt % comonomer units derived from one ofethylene and a C₄-C₁₀ alpha-olefin, and having a heat of fusion of about75 J/g or less.

Embodiment 15

The method of Embodiment 14, wherein introducing the carbon blackmasterbatch into the thermoplastic vulcanizate comprises blending thecarbon black masterbatch with the thermoplastic vulcanizate while thethermoplastic vulcanizate remains in a molten state following thedynamic vulcanization.

Embodiment 16

The method of Embodiment 14, further comprising pelletizing thethermoplastic vulcanizate so as to form a plurality of thermoplasticvulcanizate pellets prior to introducing the carbon black masterbatch tothe thermoplastic vulcanizate.

Embodiment 17

The method of Embodiment 16, wherein blending the carbon blackmasterbatch with the thermoplastic vulcanizate comprises melt-mixing thethermoplastic vulcanizate pellets with the carbon black masterbatch.

Embodiment 18

The method of any one of Embodiments 14-17, further comprisingmelt-mixing the propylene-α-olefin copolymer and the carbon black, andforming a plurality of masterbatch pellets comprising the carbon blackdispersed in the propylene-α-olefin copolymer carrier resin, such thatthe masterbatch pellets are used as the carbon black masterbatch that isintroduced to the thermoplastic vulcanizate.

Embodiment 19

The method of any one of Embodiments 14-18, further comprising passingthe thermoplastic vulcanizate through a 200 U.S. Mesh or finer screenafter introducing the carbon black masterbatch.

Embodiment 20

The method of any one of Embodiments 14-19, wherein the thermoplasticvulcanizate comprises less than or equal to 4 wt % of thepropylene-α-olefin copolymer, by weight of the thermoplasticvulcanizate, after introducing the carbon black masterbatch.

Embodiment 21

The method according to any one of Embodiments 1-13, wherein thethermoplastic vulcanizate has a surface spot count less than or equal to9 blemishes in a 1 in.×18 in. extruded strip of the thermoplasticvulcanizate.

Embodiment 22

The method according to any one of Embodiments 1-13 and 21, wherein thethermoplastic vulcanizate has an extrusion throughput rate that is about2% to about 15% faster as compared to an otherwise identicalthermoplastic vulcanizate in which all carrier resin comprising thepropylene- or ethylene-based copolymer is instead a homopolypropylenecarrier resin.

Embodiment 23

The method according to any one of Embodiments 14-20, wherein thethermoplastic vulcanizate has a surface spot count less than or equal to9 blemishes in a 1 in.×18 in. extruded strip of the thermoplasticvulcanizate.

Embodiment 24

The method according to any one of Embodiments 14-20 and 23, wherein thethermoplastic vulcanizate has an extrusion throughput rate that is about2% to about 15% faster as compared to an otherwise identicalthermoplastic vulcanizate in which all carrier resin comprising thepropylene-α-olefin copolymer is instead a homopolypropylene carrierresin.

Embodiment 25

A thermoplastic vulcanizate formed according to any of the foregoingEmbodiments.

While the present invention has been described and illustrated byreference to particular embodiments, those of ordinary skill in the artwill appreciate that the invention lends itself to variations notnecessarily illustrated herein. For this reason, then, reference shouldbe made solely to the appended claims for purposes of determining thetrue scope of the present invention. Further, the term “comprising” isconsidered synonymous with the term “including” for purposes ofAustralian law. Likewise whenever a composition, an element or a groupof elements is preceded with the transitional phrase “comprising,” it isunderstood that we also contemplate the same composition or group ofelements with transitional phrases “consisting essentially of,”“consisting of,” “selected from the group consisting of,” or “is”preceding the recitation of the composition, element, or elements andvice versa. Furthermore, all patents, articles, and other documentsspecifically referenced are hereby incorporated by reference.

The invention claimed is:
 1. A method comprising: introducing to achamber each of a thermoplastic resin, an elastomer component, a curingagent, and a carbon black masterbatch; and dynamically vulcanizing atleast a portion of the elastomer component so as to form a thermoplasticvulcanizate wherein the elastomer component is at least partiallyvulcanized and is dispersed in a continuous phase comprising thethermoplastic resin; wherein the carbon black masterbatch comprisescarbon black particles dispersed in a carrier resin comprising apropylene-α-olefin copolymer comprising at least 60 wt %propylene-derived units by weight of the copolymer having (i) a densitybetween about 0.850 and about 0.920 g/cm³ and (ii) a melt index betweenabout 0.05 and about 50 g/10 min as determined in accordance with ASTMD1238, at 190° C. and 2.16 kg weight.
 2. The method of claim 1, furthercomprising: passing the thermoplastic vulcanizate through a 200 U.S.Mesh (74 micron) or finer screen, after said dynamic vulcanization ofthe at least a portion of the elastomer component.
 3. The method ofclaim 1, further comprising melt-mixing the propylene-α-olefin copolymerand the carbon black particles, and forming a plurality of masterbatchpellets comprising the carbon black particles dispersed in thepropylene-α-olefin copolymer carrier resin, such that the masterbatchpellets are used as the carbon black masterbatch thereafter introducedto the chamber.
 4. The method of claim 3, wherein forming the pluralityof masterbatch pellets comprises underwater pelletizing the melt-mixedpropylene-α-olefin copolymer and carbon black particles.
 5. The methodof claim 1, wherein the chamber is selected from the group consisting ofa mixer, a mill, and an extruder.
 6. The method of claim 1, wherein thedynamic vulcanization is carried out at least in part by melt mixing thethermoplastic resin, the elastomer component, the curing agent, and thecarbon black masterbatch.
 7. The method of claim 1, wherein thepropylene-α-olefin copolymer comprises about 1 wt % to about 35 wt %comonomer units derived from one of ethylene and a C₄-C₁₀ alpha-olefin,and having a heat of fusion of about 75 J/g or less.
 8. The method ofclaim 7, wherein the thermoplastic vulcanizate comprises less than orequal to 4 wt % of the propylene-α-olefin copolymer, by weight of thethermoplastic vulcanizate.
 9. The method of claim 1, wherein theelastomer component comprises an ethylene-propylene-diene elastomer(EPDM).
 10. The method of claim 1, further comprising introducing to thechamber one or more additives selected from the group consisting ofplasticizers, process oils, fillers, processing aids, acid scavengers,and any combination thereof.
 11. The method of claim 1, wherein thethermoplastic vulcanizate has a surface spot count less than or equal to9 blemishes in a 1 in.×18 in. (2.54 cm×45.72 cm) extruded strip of thethermoplastic vulcanizate.
 12. The method of claim 1, wherein thethermoplastic vulcanizate has an extrusion throughput rate that is about2% to about 15% faster as compared to an otherwise identicalthermoplastic vulcanizate in which all carrier resin comprising thepropylene-α-olefin copolymer is instead a homopolypropylene carrierresin.